A number of methods for preparing 1,3,4-benzotriazepine-2-ones have been described in the literature. In general, the compounds are prepared by either of two methods from a 2-aminobenzophenone. In the first method, the 2-aminobenzophenone is treated with semicarbazide to give an aminobenzophenone semicarbazone. This product is cyclized to give the benzotriazepine-2-one. See Bull. Chem. Soc. Jap., 43, 135-138 (1970); Japanese publications 70 11,148 (CA 73:25544a) and 70 11,147 (CA 73:25545b). Alternately, a 2-aminobenzophenone hydrazone is treated with phosgene to give the desired benzotriazepine-2-one. See U.S. Pat. No. 3,176,008; J. Pharm. Sci. 63(b), 838-41 (1974) and J. Med. Chem. 7(3), 386 (1964).
Despite the reported central nervous system activity of the 1,3,4-benzotriazepine-2-ones, the thio analogues are unknown and no satisfactory method for their preparation has been described in the literature.
The sedative and tranquilization effects of 6-phenyl-s-triazolo(4,3-a) (1,3,4)benzotriazepines in mammals is described in U.S. Pat. Nos. 3,891,666 and 3,880,878. These compounds are prepared using a multi-step synthesis from an appropriately substituted 2-aminobenzophenone. The method used by the prior art to prepare these compounds is inefficient thus giving generally poor yields, and the process subjects the intermediates to a harsh oxidation step. For this reason, compounds which contain easily oxidizable moieties such as hydroxy are not readily prepared by the known method.